The present invention relates to the field of cruise control for motor vehicles and more particularly for controlling the speed of a motor vehicle via cruise control based on the position of the accelerator pedal.
Cruise control (CC) is a system used to maintain the constant speed of an automobile with the foot off the accelerator pedal. The benefits of cruise control include:                Better fuel efficiency;        Avoiding unconsciously violating speed limits;        Comfortable driving for long distances on the highway with less traffic.        
While cruise control is installed on most vehicles today, it is only good for driving conditions with very low traffic volume. When traffic increases on the road, cruise control becomes less useful. As a result, many people claim that they never or rarely use it because it is “too much trouble”. A second problem with cruise control is stepping on the brake or clutch to disengage the cruise control. This can cause the car to skid on a slippery road. Another problem is the lack of a need to maintain constant pedal pressure, which can help lead to accidents caused by highway hypnosis or incapacitated drivers.
A new type of cruise control is called adaptive cruise control (ACC) that uses a radar or laser to detect the vehicles in front, and automatically adjusts the speed for traffic, and brakes when necessary. ACC can be used regardless of the traffic. However, it is only available for some luxury models at this time. One problem with ACC is that it suffers from the “Tunnel Vision” effect (cannot see around corners, does not recognize fixed objects like trees, and fails to notice traffic merging or changing lanes). It also suffers from weather that affects the “vision” of the radar. Due to these problems, for local driving and driving on the highway with heavy traffic, taking the foot off the pedal and letting the ACC handle the vehicle is not a good idea. Besides, adaptive cruise control also produces the problem caused by highway hypnosis.
Another approach for solving the problems with the conventional cruise control is using a specially designed accelerator pedal along with controlling software to obtain constant speed. These are actually special kinds of cruise control. U.S. Pat. No. 4,541,052, U.S. Pat. No. 4,615,409 and U.S. Pat. No. 6,078,860 disclosed such kinds of speed control systems, which have the following disadvantages:    1. All these systems were developed for vehicles with electric throttle which is a drive-by-wire. While there is little doubt that drive-by-wire will become the standard in the future, most vehicles at this time still have a throttle with mechanical linkage.    2. They were designed as a total speed regulation system including accelerator pedal, throttle, engine control unit (ECU), cruise control, linkages, sensors, software and some other hardware. It is difficult to adapt these systems without fundamental changes for particular vehicle models.    3. With an electric throttle, the accelerator pedal position and the engine power output can have any kind of mapping. However, a mapping similar to the one for a mechanical throttle gives the driver a more natural driving experience. U.S. Pat. Nos. 6,078,860 and 4,615,409 divide the pedal travel path into deceleration, constant speed and acceleration ranges. Constant speeds can be maintained at a “natural position”, which is at 25% of the pedal path for U.S. Pat. No. 6,078,860, or at a “0” point, which is between 10% and 40% for U.S. Pat. No. 4,615,409. In both cases, the 0 acceleration point is implemented by hardware with springs. It is not natural to have a single position corresponding for all constant speeds, and it is not natural to pass through 10% to 40% of the travel path to start acceleration. The system in U.S. Pat. No. 4,541,052 assumes a linear relation between the pedal position and the engine output power. Again, this is not natural. These special pedal and engine output mapping schemes make it difficult for various motor vehicle models to adapt to these technologies. U.S. Pat. No. 7,000,722 reveals a special accelerator pedal which can be used to resume cruise control. This device is only good for vehicles with an adaptive cruise control.